Method of toning photographic images



Patented Apr. 4, 1944 METHOD OF TONING PHOTOGRAPHIC IMAGES Howard A. Miller, Rochester, N. .Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey t No Drawing.

Application November 25, 1941, Serial No. 420,369

11 Claims. (CI. 95-88) Thi invention relates to photographic images. i

It is well known that photographic silver images may be converted to a form in which they can be toned with sulfur compounds such as sodium sulfide to vary the color of the image. The dominant hue of the silver sulfide image formed in this way or of similarly formed silver selenide or telluride images varies with the nature of the photographic emulsion employed. Frequently the print yields a tone which is too purple or cold and it is desirable to produce animage having a warmer tone.

-It is, therefore, the principal object of the present invention to provide a method for producing a. warm toned photographic image. A further object is to provide a method for regulating the tone of the photographic image in the "indirect process of sulfide toning. Other objects will appear from the following description of my invention.

These objects are accomplished by treating the photographic image to be toned in a bath containing thio'acetamide or a thiourea as a toning agent and also containing as a restraining agent one or more of various sulfur compounds.

The restraining agents used according to my a method for toning invention include thiobarbituric acid, rhodanine,

substituted thiohydantoins such as 1-acetyl-2- thiohydantoin and 1-benzoyl-2-thiohydantoin.

dialkyl-substituted thioureas, thio'benzanilide and thioacetanilide. These restraining agents are used in amounts varying from 0.1 gram to 2 grams or more per liter of the toning solution.

My invention is preferably used in the "indirect process of sulfide toning photographic prints. In this process a developed and fixed photographic image is bleached in a solution such as ferrlcyanide and bromide or potassium permanganate and hydrochloric acid which converts the silver image to a silver salt and is then washed and toned in a solution or a sulfide or other sulfur toning agent (Neblette Photography Principles and Practice, 2nd edition, 1930, page 440). 7

According to the preferred embodiment of my invention, after treatment of the silver image with the bleaching solution of ferricyanide and bromide, it is toned in a sulfur toning bath consisting of an alkaline solution of thioacetamide Or a thiourea containing one of the restraining agents specified above. By the addition of increasing concentrations of these restraining agents to the toning bath, prints were produced typical toning procedure will be described.

After exposure, development and fixing of pho-' tographic prints on paper, the silver images were bleached in a solution of the following composition:

Potassium ferricyanide grams 20 Potassium bromide do 20 Water to liter 1 This bleach bath converted the silver images to a silver salt or salts capable of being toned.

The prints were then rinsed and a check print was treated in a solution of the following composition:

Thioacetamide grams 1 Borax do 10 Water to liter 1 The tone produced by this treatment was the typical cold tone resulting from sulfide toning without the use of a restraining agent.

Toning solutions were made up containing various restraining agents and having the following composition 1. Thioacetamide grams 1 Borax do 10 Thiobarbituric acid do 0.1 to 2 Water to liter 1 Thioacetamide grams 1 Borax d 10 Thioacetanilide do 0.1 to 2 Water to liter 1 3. Acetyl thiourea grams 1 Sodium carbonate "do-.." 10

' Thiobarbituric acid do 0.1 to 2 Water to liter 1 Upon treatment of the bleached prints in these solutions containing various amounts of the restraining agents, it was found that upon increasing the amount of restraining agent the tone of the prints became warmer until a very yellow brown image was produced with the solutions containing 2 grams per liter of the restraining agent.

The toning baths may be used in alkaline solutions such as solutions containing sodium carbonate or borax. Although some of the restraining agents which I propose to use have previously been suggested for use in toning solutions, none of them has any toning action alone in borax image n. tho x sqlutien-ofi his a en el t d m thiobarbituricz; acid-,rhodanine lj-acyl- -th iohyimage: in arboraxsolutioniiof thloacetam 1retaining.thiobarbituric acid 14*. The methodsof TESH'QlHIDgQCQI producingv warm tones. in:1to,ni-ng,a photographic lu The restraining agents are intended for use only in conjunction with sulfur toning agents and have no toning action when used alone.

It will be understood that my invention is susceptible of variations which will be apparent to those skilled in the art and that my invention Iclaim: 1. The method of restraining cold tones and producing warm tones in vtpnirig3a,. ol ,otog raphic silver salt image, which conip'ris'e's" t'reati'n thef sco e of-theapimage in an alkaline solution of a toningag'ent selected from the group consisting of acetylthiourea and thidacetamide, containing a ffestraining agent selected from the group consisting of thiobarbituric acid, rhodanine, l=acyl-2. thiohy dantoins, dlalky1 thioureas, thiobenzanilide and thioacetanilide.

2. The method of restraining cold"tones -'and l plf d n i actmi tent nin s P PQ KE treating the silver salt image, which compi lected'; from .-the: group consist 4 1 aa v o e am lleeao nta n h isr i dantoins, dialkyl thioureas, thioacetanilide.

3' "The method of thiobenzanilijde, and

ide conamide, containing "a restraining agent selected from the class consisting of thiobarbituric acid, 5

veloping and fixing a sensitive silver halide layer, t treating: the-. layer with at/ ferricyanide and brojmidef'solutioii to form a Si1Y 1' salt image, and

then toning said silver salt image in a borax solution of a toning agent selected from the group consisting of acetyl thiourea and thioacetamide,

" containing a-testraining agent selected from the class consisting of thiobarbituric acid, rhodamne, l-acyl-z-thiohydantoins, dialkyl thioureas, thiobenzanilide fand thioacetanilide.

'8.-,The method of producing a warm-tone photographic image .which comprises exposing, de-

- 'veloping and fixing a sensitive silver halide layer,

silver salt image, which comprisestreating ,thei

imag e in a borax solution of thioagetarnide containing 'thioacetanilide. n

5, The method of restraining cold tones and producing warm tones in oping and fixing a sensitive silver halidelayer, treating the 1ayer with a ferricyanideand bromide solution to form a silver salt image, and

:then toning said silver salt image in analkaline V solutionpof a toning agent selectedjrom the group consisting of acetyl thiourea and thioacetcontainingthiobarbituric acidl' ,"W restra ning cold tones and I f thiohydantoins; dialkyl thioureas, lide, andthic; cotanilida;

" treating the layer with a ferricyanide and bromide solution to form a silver salt image, and then toning said silver salt image in a borax solution of 'a tonihgag'erit s'elected'fr'om the group consisting of acetyl thiourea' and thioacetamide,

9; The method" of 'produci'riga warm-tone phov togra'phic image whi'c'hborriprises "exposing, de-

velopin'g a'nd fixinga sensitive silver halide layer,

- treating the'layerwith-a ferricyanide and bromide-solution form a silver' salt image; and

thentoning' said' silver salt image'in a borax so- Dro'iucing warm tones inton'ir'i'g' a*ph'otographic lutiofi of thin crtla'zmid containing thiobarbituric acid,

10: The method of-fproducing a-warmetonephotographic image which comprises exposing, de-

wvelo'pingandrfixing a sensitive-silver halide layer,

treating the layerswitha ferricyanide and broamide solutiontoxforma silver-salt'image, and then toning said silver saltimage in a'borax solution of thioacetamide -containinge thioacetjanilide."

a; 11-. The method-of restraining cold tones and producing warm tones in toning a photographic silver salt image, which comprises treating the image ina sodium carbonate solution of' a toning agent selected-from thegroup consisting of acetyl -thiourea-and thioacetamide, containing a restraining agent; selected irom the group consisting of thiobarbituric .acid, rhodanine, l-acyl-iithiobenzani- .iH W R Q AQMILLER. 

